An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri - Paris Observatory

A transient upper atmospheric phenomenon occurring over a
→ thunderstorm in the lower
→ ionosphere. Elves result from
especially powerful electromagnetic radiation pulses
that are generated from certain lightning discharges
(→ sprite). As the energy passes
upwards through the base of the ionosphere it causes the gases to
briefly glow for
less than a thousandth of a second. This makes elves virtually
impossible to see with the naked eye. Elves occur at a height of around 90-95 km,
and can expand outward to several hundred kilometers in diameter,
like giant expanding doughnuts.

Short for:
Emission of Light and Very low-frequency perturbations from
Electromagnetic pulse sources.